Organic sulphide polymers and mineral oil compositions containing same



Patented Apr. 30, 1 940 UNi ED STATES PATENT- OFFICE ORGANIC SULPHIDE POLYMERS AND IVHN- ERAL OIL COMPOSITIONS CONTAINING SAME ware

No Drawing. Application August 21, 1936, Serial No. 97,197

12 Claims.

- This invention relates to improved oxidation inhibitors and their use in mineral oil compositions and more particularly to the addition of certain organic sulphur compounds to mineral oils in order to improve their properties, particularly with respect to stability when used at elevated temperatures such as in use as lubricants in internal combustion engines.

In a co-pending application Serial No. 51,827, filed November 2'7, 1935, by Louis A. Mikesk'a and Charles A. Cohen, there is described the use of certain substituted aryl thioethers as stabilizing agents for mineral oils. In a second co-pending application, Serial No. 93,764, filed August 1, 1936, by the present inventors, there is described the use of a class of substituted aryl polysulphides for the same purpose. It has now been discovered that the higher reaction products, particularly dimers and trimers, of these two classes of organic sulphur compounds, also possess many desirable characteristics as mineral oil stabilizing agents.

Compounds suitable for the present invention are represented by the following formula:

OH I OH OH OR" where R is an alkyl group of preferably 2 to 8 carbon atoms, although larger and smaller alkvl groups are not excluded. R and R" are preferably the same as R, but may also be any other alkyl group or H, and B. may represent different alkyl groups and H in different groups of the same molecules-when y is greater than 1; y is an integerjrom l to 6 and is preferably 2 or 4; n and 11' represent integers from 1 to 4 and are preferably 1 or 2, and n may represent different integers in different groups of the same molecule, when 11 is greater than 1. The linkage between the aromatic nuclei of the radicals illustrated is preferably through the sulphur. The benzene ring also represents polycyclic rings such as diphenyl and condensed aromatic nuclei such as naphthyl.

The use according to this invention of other derivatives of the alkyl phenol sulphides which contain other substituent groups in addition to the hydroxy and alkyl groups, is also contemplated. Such additional substituent groups should not, however, offset the solubilizing effect of, the alkyl groups to an extent suflicient to render the compound insoluble in lubricating oil. Examples of suitable groups or radicals which may be attached to either the aryl or the alkyl group, are alkyl and aryl hydrocarbon radicals,

also such radicals containing oxygen, such as ether, aldehyde, ketone, acid and ester radicals, those containing nitrogen such as amines and CN and those containing sulphur, selenium, tellurium and thelike.

The sulphur atoms present in the polysulphide linkage of the alkyl phenol sulphides may also be wholly or partly replaced by the heavier ndnmetallic elements of group 6, such as selenium and tellurium.

Preferred examples of thisclass of compounds are indicated by the following formulae, together with suitable methods for the preparation of these classes of compounds.

ROH

. R R OH R OH R a R on R on R v. HoQsOsOa-Oon The formulae illustrated are purely diagrammatic and the hydroxyl and alkyl radicals are not limited to the positions shown therein. Each of these radicals may be connected to any position in the benzene ring, but those compounds in which the alkyl radicals are in ortho or para position to the hydroxyl group are preferred.

While these compounds may be added in any desired concentration I within their solubility limits to lubricating oils, they are preferably used in concentrations of about 0.1 to 2.0% and a concentration of about 0.5% will befound sufllcient to stabilize the majority of petroleum lubricating oils. These compounds may be prepared by various methods.

, One method for preparing a compound of Class I is to bring the corresponding 'alkyl phenol into reaction with sulphur dichloride in a mol ratio of sulphur dichloride to phenol between about 1 and 1.5, preferably from about 1.2 to 1.4. By this means both the alkyl phenol sulphide and polymers thereof are formed. The alkyl phenol sulphide is separated from the polymers in the reaction product by distillation under vacuum;

the polymers being obtained as a residue. This reaction is preferably conducted in the presence of an inert solvent, preferably an alkyl halide such as ethylene chloride, at a temperature of about 60 to 140 C. and preferably from about to C. The solvent preferably boils at the reaction temperature and the reaction is conducted under reflux until the hydrogen chloride formed thereby is completely eliminated. This process is described in the co-pending application of Mikeska and Lieber referred to above.

A second and preferred method for preparing polymers of this type is to bring a dialkyl diphenol sulphide into reaction with sulphur dichloride, using about 2 mols per mol of sulphur dichloride. This reaction may be conducted in the same solvents and with the same reaction conditions described above. By this means a substantially theoretical yield of the dimer is obtained without the formation of undesirable and insoluble highly polymerized products.

Compounds of Class II may be prepared by bringing a dialkyl diphenol sulphide into reaction with sulphur mono-chloride in the same solvents and under the same reaction conditions described above, using preferably about 2 mols per mol of sulphur mono-chloride.

Compounds of Class III may be prepared by bringing an alkyl phenol into reaction with a slight excess of sulphur monochloride, using a mol ratio of between about 0.5 and 0.75 and preferably between 0.6 and 0.7 mol of sulphur monochloride per mol of the alkyl phenol. By this means both the alkyl phenol disulphide and polymers thereof are formed. The polymers may be separated from the monomer by extraction with selective solvents, or by other suitable means. by bringing a dialkyl diphenol disulphide into reaction with sulphur monochloride, using about 2 mols per mol of sulphur mono-chloride. These reactions may be conducted in the same solvents and with the same reaction conditions described above.

Compounds of Class IV may be prepared by bringing dialkyl diphenol disulphide into reaction with sulphur dichloride in the same solvents and under the same reaction conditions described above, using preferably about 2 mols of the alkyl phenol disulphide per mol of sulphur dichloride.

Compounds of Class V may be prepared by bringing a dialkyl diphenol tetrasulphide into reaction with sulphur mono-chloride, using preferably about 2 mols of tetrasulphide per mol of sulphur mono-chloride.

All the above preparations may be conducted in the solvents and under the reaction conditions described in connection with compounds of Class I.

Higher polymers may also be obtained by using slightly higher ratios of the sulphur chloride reagent to the phenol or by bringing any of the polymers above described into further reaction with sulphur dichloride or sulphur mono-chloride under the same conditions already described.

The following example is presented to illustrate one process for preparing the compounds of this invention.

EXAMZPLE I grams of ditertiary amyl diphenol sulphide (2 molar proportions) are dissolved in 500 cc. of ethylene chloride and the solution is heated to boilingunder reflux. 18 grams (one molar proportion) of sulphur dichloride were dissolved in, 100 cc. of ethylene chloride. This solution was added with stirring to the boiling solution of the amyl phenol sulphide. The hydrogen chloride gas evolved during the reaction was with- Such polymers may also be prepared.

drawn from the reaction zone through the reflux condenser. When the addition of the sulphur dichloride solution was completed, the boiling of the reaction mixture under reflux was continued for six hours until no further emission of hydrogen chloride was apparent. By this means, all hydrogen chloride is removed and there is no need to wash the reaction product with water. The time of refluxing can be cut down by blowing an inert gas such as nitrogen or flue gas through the reaction mixture. This may be done during the reaction or after all the reagents have been added, as desired.

The solvent, ethylene chloride, was then removed from the reaction mixture by distillation and the resulting product was distilled under vacuum. The products obtained were:

1. Distillate to 250 C- at apressure' of 3 mm. of mercury; 0 gram of unreacted phenols.

2. Distillation residue; 134 grams of ditertiary amyl diphenol sulphide polymer.

The yield of amyl phenol sulphide dimer recovered as residue was 100%; based on the original amount of diamyl diphenol sulphide.

It was a dark red, translucent, viscous liquid which is soluble in ether, alcohol, acetone, carbon disulphide, liquid hydrocarbons, hydrocarbon halides, petroleum oils and fractions thereof, including gasoline, kerosene, burning and Diesel oils and lubricating oils, and in most or anic solvents.

The compounds prepared according to this invention greatly stabilize mineral lubricating oils at elevated temperatures, especially the highly refined oils such as synthetic oils, solvent extracted oils obtained by treatment of mineral lubricating oils with single solvents such as phenol, dichlorethyl ether, furfural, propane, nitrobenzene, crotonaldehyde, etc., or by double .cr multiple solvents such as propane-cresol, etc., clay or acid treated oils, also aluminum chlo-- ride treated oils, white oils, hydrogenated oils, and the like. These compounds are especially effective with such oils having viscosity indices above 60, 80, 100 or more. Lubricating oils also stabilized by these compounds are other mineral oils of over 35 or 40 viscosity Saybolt at 210 F., and even those having a viscosity of over 100 seconds at 100 F., either in the crude form or partially or highly refined by distillation, voltolization, chemical reagents, and adsorptive agents, as well as coal tar or shale distillates, pale oils, neutrals, bright stocks and other residual stocks, cracking coil tar fractions,'condensed or polymerized fractions, and the like, either waxy, dewaxed, or non-waxy.

The lubricants to which these stabilizing agents are added may also contain dyes, metallic or other soaps, pour inhibitors, sludge dis-' persers, oxidation inhibitors, thickeners, V. I. im-

ters of the acids obtained by limited oxidation'of 75 l tration.

0.1 and 5.0% of-the total composition, and 0.5,

, steel surface and the oil.

paramn wax may be used, for example, the isopropyl esters of oxidized wax acids which are substantially monobasic. The hydroxyl groups of the alkyl phenol sulphide polymers may also 5 be partially or completely esterified with an organic acid, preferably a fatty acid. These esterified compounds may be mixed with other nonesterified alkyl phenol polysulphides. The oiliness agent may be used in any suitable concen- The amount used is usually between 1.0 to 2.0% is generally sufficient The following examples illustrate the use of the compounds described herein as stabilizing agents 5 in lubricating oils.

EXAMPLE II V 0.2% of the dimer of ditertiary amyl diphenol sulphide dimer, illustrative of the compounds of Class I, was blended with an S. A. E. 20 lubricating oil derived from petroleum. A blend of the same concentration of ditertiary arnyl diphenol sulphide was also prepared with a sample of the same oil. Oxidation rates, Sligh numbers It will be noted that the polymer reduced not only the cone number even more than did the :0 amyl phenol sulphide, but it also reduced the Sligh number of the original oil to a point at which sludge was almost inappreciable, while the amyl phenol sulphide had very little effect on the Sligh number.

L5 The methods of testing in the above example are as follows:

Cone test.'Ihis method is a means for determining the tendency of an oil to deposit solid matter upon heated metallic surfaces. It consists in slowly dropping the oil to be tested over a heated metal (generally steel) cone, having a circumferential groove milled out in a screw fashion on the periphery so-as to allow a time of contact of about one minute between the heated A total volume of 60 cc. of oil is dropped from a dropping funnel during a period of 2 hours to obtain this time of contact. The temperature of the cone may be any desired value, but for lubricating oils 250 C.

, is preferable since it represents approximately Sligh test-The tendency of an oil to sludge under oxidizing conditions is described in Proc. 0 A. S. T. M. 24, 964, II (1924), except that the oxidation is continued for 24 hours.

Corrosion test.-'I'his consists in immersing a bright copper strip for three hours in the oil maintained at 212 F. It is used to determine 5 the presence of corrosive sulphur in oil, which is indicated by discoloration or pitting of the copper strip.

EXAMPLE III Runs under closely comparable conditions were made in a C. F. R. (Cooperative Fuel Research) engine with a highly refined petroleum lubricating oil of 72 seconds Saybolt viscosity at 210 F. and with blends of 0.2% of ditertiary amyl diphenol sulphide (A) and of the dimer thereof (B), prepared as in Example I, in separate portions of the same oil. After each run the engine was taken down, inspected and rated by demerits according to the condition of the piston parts, valves and cylinder. On this scale the demerit rating is higher as the engine condition is worse. The runs were each made for 14 hours at a jacket temperature of 375 F. The results are given below:

C. F. R. engine tests Blends Blank Demerit rating 5. 2 2. 3 1. 9

Other polymers of other alkyl phenol sulphides may also be used for preparing improved lubricating oil compositions of high stability in the manner described in the above examples. Such compounds preferably have at least one alkyl group of about 2 to 8 carbon atoms. Compounds containing two alkyl phenol groups in which the alkyl radicals contain about 4 to 6 carbon atoms are preferred. The alkyl groups may be normal, iso, secondary or tertiary. They may also be cycle but the open chain alkyl groups are preferred. The polysulphide compounds may be either symmetrical or unsymmetrical, i. e., containing difierent alkyl and/or aryl radicals. The aryl radicals may be polyhydroxy including such groups as those derived from resorcinol, hydroquinone and their allgvlated and arylated derivatives. They may also contain condensed aromatic nuclei such as those derived from naphthol and its corresponding derivatives, and may beotherwise unsubstituted, or may be substituted in the ring as described above.

This invention is not to be limited to any specific examples, all of which have been presented solely for the purpose of illustration, but is to be limited only by the following claims, in which it is desired to claim all novelty insofar as the prior art permits.

We claim:

1. A composition of matter comprising a mineral lubricating oil containing dissolved therein a polymer of a diary] sulphide having at least one hydroxy group attached to each aromatic nucleus.

2. A composition of matter comprising a mineral oil containing in solution a compound having the formula OH OH OH where R is an alkyl group, R and R" are alkyl lution in an amount effective to increase the sta-.

bility of the oil under oxidizing conditions a compound having the formula where R. is an alkyl group, the radicals OH, R. and S each being connected to an aromatic nucleus.

4. An improved lubricating composition comprising a mineral lubricating oil containing in solution in an amount efiective to increase the stability of the oil under oxidizing conditions a compound having the formula R R 0 II R O H R where R is an alkyl group, the radicals OH, R, S and S2 each being connected to an aromatic nucleus.

5. An improved lubricating composition comprising a mineral lubricating oil containing in solution in an amount effective to increase the stability of the oil under oxidizing conditions a compound having the formula R R OH H. OH R 8. A mineral lubricating oil containing about 0.01 to 1% of a compound having the formula where R. is an alkyl group, the radicals OH, R, S, and $2 each being connected to an aromatic nucleus.

9. An improved lubricating composition com-.

prising a mineral lubricating oil having dissolved therein in an amount sufficient to increase the stability of the oil under oxidizing conditions a dimer, having a sulphur linkage, of ditertiary amyl diphenol thioether.

10. An improved lubricating composition comprising a mineral lubricating oil containing in solution an alkyl phenol sulphide product of the reaction of an alkyl phenol and a sulphur chloride, said product having more than 2 phenol radicals per molecule.

11. An improved lubricating composition comprising a mineral lubricating oil containing in solution in an amount effective to increase the stability of the oil under oxidizing conditions, a polymer of a di-alkyl diphenol sulphide, prepared by condensation of said di-alkyl diphenol sulphide with a sulphur chloride, said alkyl groups having from 4 to 6 carbon atoms each and said polymer being a viscous liquid which is unvapor- 'ized at 250 C. at a pressure of 3 mm. of mercury.

12. Composition according to claim 11 in which said polymer is a product of condensation of ditertiary amyl diphenol thioether and sulphur chloride. I

EUGENE LIEBER. LOUIS A. MIKESKA. 

